Pros: free drinks, free food (sometimes), pick and choose hours, benefits
Cons: lots of work with little support (starbucks under-staffs their stores to make more money), pay is terrible with little chance for substantial raises
As a barista working in the afternoon, other than dealing with customers, your primary job is to clean everything. Either (almost) everything behind the counter, or the rest of the store (sweeping, moping, bathrooms, restocking).
It's fun working with people all the time and becoming a part of the community. Starbucks has helped me come out of my shell and has played a big part in me becoming the outgoing person that I am.